1. Field of the Invention
The invention relates to latching and locking devices for gates and the like adapted for at least partial security.
2. Description of the Prior Art
In the prior art, locks and latches of many descriptions have evolved for use on doors, gates and the like. The degree of security justified in the design and application of such locks and latches is determined by the possible consequences of unauthorized or surreptitious entry.
A gate, for passage through a fence, for example, ordinarily does not require a high order or entry security because an intruder may be able to simply scale the fence or gate or otherwise breach the barrier. An important degree of security against the casual intruder is often obtainable if only the latch operator is unobvious.
Typically of the state of the relevant prior art in latches and locks generally are U.S. Pat. Nos. 1,489,675; 3,206,954; 2,700,292; 4,179,143; 1,187,756; 2,671,683; 2,466,855; 3,692,342 and 3,709,538.
U.S. Pat. No. 1,489,675 shows the classical and ubiquitous spring door latch (key opened or locked).
U.S. Pat. No. 3,206,954 describes a variation of the classical spring latch door lock in which operation is by normal force (pull or push depending upon which door side the operator is positioned) rather than by door knob rotation.
U.S. Pat. No. 2,700,292 depicts another form of knob or handle operated, key-lockable, door latch assembly in which the latch member rotates in a plane parallel to the plane of the door and rides up, over and behind a sawtooth strike plate on a door frame in lieu of the usual horizontally translated latch member.
U.S. Pat. No. 4,179,143 shows a simple "barrel bolt" type of translating latch member with means for latching in the extended direction and quickly releasing for spring induced withdrawal.
A barn door spring latch mechanism without keying or other locking features in shown in U.S. Pat. No. 1,187,756. No security features are included.
U.S. Pat. No. 2,466,855 is a compressed-air operated lock for freight car doors intended for high order security against surreptitious entry by persons not equipped with the required compressed-air apparatus.
U.S. Pat. No. 3,692,342 is entitled "Container, Post Locking Member" but does not appear to be an operative latch or lock device. Rather, it is an assembly apparatus for a knock-down container on a pallet base structure such as used in commercial shipping
U.S. Pat. No. 3,709,538 shows a device for securing a cover (hinged or otherwise) on a chest or receptacle with easy release. No security features are disclosed.
A gate latch constituting somewhat more pertinent prior art vis-a-vis the invention is disclosed in U.S. Pat. No. 2,671,683. No security features are contemplated and the operation is immediately obvious, even to a casual observer.
None of the aforementioned prior art disclosures address the requirement for any operatively non-obvious gate latch device also capable of being simply locked for additional security.
The manner in which the invention deals with the inadequacies of the prior art to provide a relatively simple, but greatly improved, lockable latch device, for a gate or the like, will be evident as this description proceeds.